Adjustable gas block for an indirect gas operated firearm

ABSTRACT

A firearm including a barrel, receiver, indirect gas system and an adjustable gas block designed to interface with the indirect gas system is provided. Four indexable positions of adjustment are provided for on the adjustable gas block. Positions of adjustment are selected based on the use of a silencer, use of under-powered ammunition, the presence of un-burnt powder and debris in the host firearms operating system, or if the weapon is being fired under “ideal” circumstances. The provided gas block is designed to function with an indirect gas operating system. Excess gas from the operating system is not vented from the gas block thereby generating excess flash and sound. No tool is required to manipulate the adjustment mechanism of the gas.

This application is a continuation of U.S. patent application Ser. No.12/929,928, filed Feb. 24, 2011, now U.S. Pat. No. 8,752,473, which is acontinuation of U.S. patent application Ser. No. 12/220,725, filed Jul.28, 2008, the disclosure of each of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This present invention generally relates to self loading firearms,specifically to gas blocks for self loading firearms which facilitateuser adjustment of the gas flow from the barrel into the operatingsystem.

2. Description of the Related Art

The need to regulate the gas flow between the barrel and operatingsystem of a firearm has been a concern since the introduction ofautoloading firearms. Gas is generated during the combustion of gunpowder present in the cartridges used in modem firearms; 20 This gasexpands violently to push the bullet out of the firearm's barrel. Theseexpanding gases are utilized as a means to operate the action of thehost firearm. In modem firearms the preferred method of facilitating thefunction of an autoloading weapon is as follows. A hole is placed thruthe barrel, generally on the top. Location of this hole or gas portvaries between operating systems. Generally a gas port size is chosen toallow a broad range of 25 ammunition to be utilized while guaranteeingthe reliable function of the host firearm. Unfortunately due to varyinglengths of barrels, ammunition variance, and other factors it is verydifficult to choose a gas port size which universally works under allconditions. A popular way of dealing with these problems is toincorporate an adjustable gas block into the operating system.

An adjustable gas block allows for the flow of gas between the gas portin the barrel and the operating system of the firearm to be increased ordecreased based on mitigating factors present at the time of use. Thesesystems typically work by utilizing an oversized gas port with means toadjust the flow of gas into the operating system and by venting theunneeded gases from the barrel into the atmosphere thus generating flashand sound. Further, adjustment of the gas system typically requires aspecial tool and offers no way for the user to index the system and makeadjustments due to mitigating circumstances quickly. Designs such asthese are well known in the prior art and can be found on the Belgium FAL, Soviet SVD and the Yugoslavian M76 rifle.

Recent firearm designs such as the FN SCAR rifles have incorporatedadjustable gas blocks to be used in conjunction with noise suppressors.Noise suppressors provide a means to redirect and expand the gasesgenerated from the discharge of a firearm so that the resulting flashand sound generated by the firearm is minimized or eliminated. As aresult, back pressure is generated forcing more gas into the firearm'soperating system. This extra gas, or back pressure increases the firingrate of a weapon during its full auto function, fouls the weapon leadingto premature malfunction and to a variety of feeding and extractionproblems.

Modern rifle designs such as the FN SCAR Rifles incorporate adjustablegas blocks which have adjustable pre-set positions. Typically two orthree positions of adjustment are afforded the user. A reduced gas flowsetting on an adjustable gas block is generally present due to militaryand government agency requirements. Reducing the standard gas flow isdesirable when a silencer is to be used. Silencers increase backpressure and the cyclic rate of the host firearm. By reducing the amountof gas directed to the operating system under normal circumstances, thesilencer, with the increased pressure it generates, should not affectthe weapon's operation significantly. While designs with an adjustablegas block mitigate the potential problems associated with the increasedback pressure and fouling a noise suppressor generate, gases are stillvented out of the gas block thus generating flash and sound. Generatingflash and sound from the gas block is counter productive to the functionof the silencer which is attempting to reduce the flash and sound fromthe muzzle of the host firearm.

The present invention offers several advantages over the prior art. Fourpositions of adjustment are provided for. Position one offers a“standard” flow of gas. This position is optimized for the firearmsbarrel length and caliber. Position two reduces the flow of gas into theindirect gas operating system so that with the addition of a silencerthe indirect gas operating system is still receiving an equivalentamount of gas as was being provided by position one when no silencer wasbeing utilized. Position three blocks the flow of gas between the barrelgas port and the indirect operating system. This position optimizes thesound reduction capability of an attached noise suppressor. Positionfour increases the amount of gas being communicated to the operatingsystem so that the firearm may operate properly while dirty or whenunder powdered ammunition is being utilized. Each of the aforementionedpositions of adjustment are indexed with a spring and ball detent, andare pre-set at the factory. No tool is required to rotate the adjustmentcylinder into one of the four positions. There is no vent in the gasblock which allows for excess gas or un-burnt powder to exit.

SUMMARY OF THE INVENTION

Accordingly several objects and advantages of the present invention are

(a) To provide the user an indexing means to adjust the flow of gas intothe operating system of a firearm.

(b) To provide a device which restricts the flow of gas into theoperating system without venting excess gas from the gas block.

(c) To provide an adjustment mechanism which does not require the use ofspecial tools.

(d) To provide an adjustable gas block that may be utilized with anindirect gas system.

(e) To provide an adjustable gas block with a means to provide gas thatis in excess of what is required to help the weapon function in adverseconditions or with underpowered ammunition.

In accordance with one embodiment of the present invention, a firearm isprovided comprising a receiver, a barrel, an adjustable gas block for anindirect gas operated firearm and an indirect gas system. The adjustablegas block is fixedly secured to the barrel and aligned with the gas porthole located thereon. A rotating cylinder provides an indexing,adjustment means for the gas block. By rotating the provided cylinderthe flow of gas between the barrel and the indirect gas system is eitherincreased or decreased. Four position of adjustment are afforded theuser: A standard gas flow, suppressed gas flow, no gas flow, and anadverse conditions gas flow setting. For adverse conditions the gas flowis increased over what the host weapon would typically require tocompensate for a dirty operating system.

Still further objects and advantages will become apparent from aconsideration of the ensuing description and drawings.

DESCRIPTION OF THE DRAWINGS

The novel features believed to be characteristic of the presentinvention, together with further advantages thereof, will be betterunderstood from the following description considered in connection withthe accompanying drawings in which a preferred embodiment of the presentinvention is illustrated by way of example. It is to be expresslyunderstood, however, that the drawings are for the purpose ofillustration and description only and are not intended as a definitionof the limits of the invention.

FIG. 1 is a side perspective view of an adjustable gas block for anindirect gas operated firearm in accordance with the present invention;

FIG. 2 is an exploded view thereof;

FIG. 3 is a partial cutaway view of the nozzle assembly and adjustmentknob;

FIG. 4 is a side cutaway view of the adjustable gas block for anindirect gas operated firearm;

FIG. 5 is a side perspective view of an autoloading rifle, with theadjustable gas block for an indirect gas operated firearm in place.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The adjustable gas block for an indirect gas operated firearm 1 isdesigned to provide four positions of adjustment, each of which affectsthe flow of gas from the barrel gas port into the operating system ofthe host firearm. The herein disclosed device is designed for anindirect gas operating system, it should be noted however that thisdevice is not limited to such operating systems and in fact could beutilized with a gas impingement operating system such as is found on theM16 family for firearms.

Turning now to the drawings in which like reference characters indicatecorresponding elements throughout the several views, attention isdirected to FIG. 1 which illustrates the preferred embodiment of theherein proposed invention. The adjustable gas block for an indirect gasoperated firearm 1 is a replacement for a standard gas block, well knownin the prior art, for an autoloading firearm. The adjustable gas blockfor an indirect gas operated firearm 1 is comprised of a housing 10,adjustment knob 20, nozzle assembly (piston) 30, and a front sight 60.

In FIG. 2, there is illustrated an exploded view of the adjustable gasblock for an indirect gas operated firearm 1 and all of its components.The gas piston block 10 has a piston receiving channel 13 which islocated above the barrel receiving channel 12. Near the distal end ofthe gas piston block 10 is located a placement 14 for the adjustmentknob 20. Located along the bottom of the gas piston block 10 are twothru pin placements which are utilized to secure the unit as a wholeabout a barrel. A front sight 60 is provided for on the distal end ofthe gas piston block 10 along with a bayonet lug 70.

The preferred embodiment piston 30 consists of a proximal end, middleand a distal end. On the proximal end is an end wall 33 which blocks theproximal opening entirely. A thru pin bore 34 is present proximate theproximal end. Near the middle of the piston 30 are the connecting member39, the radial flange 40, and the diameter-reducing transition portion41. At the distal end is a nozzle 31 which provides an opening into theinterior of the piston 30.

The adjustment knob 20 has a series of slots 25-28 which run transverseto the axis of the piston void 29 located in the center of theadjustment knob 20. The slots 25-28 are located on the front of theadjustment knob 20. A thru pin bore 24 is present on the exterior of theadjustment knob 20 and is designed to receive a thru pin 21.

In FIG. 3 there is illustrated a view of the adjustment knob 20 and thenozzle assembly 30. The nozzle assembly 30 is partially cut away toreveal the three gas ports which are 45 degrees offset from one anotherproximate the connecting member 39. Gas port one 35, gas port two 36,and gas port three 37 are each unique in size. These gas ports 35-37 allintersect in the center of the nozzle assembly 30.

FIG. 4 illustrates a cutaway view of the adjustable gas block 1. The gaspiston block 10 houses a spring 22 and ball detent 23. A porthole 44thru the gas piston block 10 is in communication with the nozzleassembly 30. The nozzle assembly has a bore 38 which is in communicationwith the nozzle 31 and the porthole 44 located in the gas piston block10. The adjustment knob 20 is secured about the nozzle assembly 30 bymeans of a thru pin 21 placed into the thru pin bore 24.

FIG. 5 illustrates a perspective view of a firearm receiver 90 connectedto a barrel 101 utilizing a removable rail 91 which incorporates anindirect gas operating system 100 and the gas piston block 10.

As used herein, the word “front” or “forward” corresponds to directionright of the gas piston block 1 (i.e., to the right as shown in FIGS. 1thru 5); “rear” or “rearward” or “back” corresponds to the directionopposite the direction of the gas piston block 1 (i.e., to the left asshown in FIGS. 1 thru 5); “longitudinal” means the direction along orparallel to the longitudinal axis of the gas piston block 1; and“transverse” means a direction perpendicular to the longitudinaldirection.

The adjustable gas block 1 receives a portion of a firearm barrel 101inside of the gas piston block 10 in the barrel receiving channel 12.Two thru pin placements 15 spaced apart along the bottom of the gaspiston block 10 receive two thru pins which prevent rotation orlongitudinal movement of the adjustable gas block 1 along the length ofthe barrel 101. The piston receiving channel 13, located above thebarrel receiving channel 12, has an opening which runs parallel to thebore line of the firearms barrel 101. Between the front site 60 and thepiston receiving channel 13 is a placement 14 which houses theadjustment knob 20. The adjustment knob 20 has a centrally located void29 which receives the proximal end of the nozzle assembly 30. The nozzleassembly is 30 housed within the piston receiving channel 13 and void 29located within the adjustment knob 20. Thru pin bore 24 is located onthe adjustment knob 20 and another thru pin bore 34 is located on theproximal end of the nozzle assembly 30. These two thru pin bores arealigned and a thru pin 21 is utilized to secure both the nozzle assembly30 and the adjustment knob 20 together. A spring 22 and ball detent 23are located under the piston receiving channel 13 where the ball detent23 interfaces with the four indexing notches 25-28 located about thedistal or rear end of the adjustment knob 20.

Four positions of adjustment are provided for. Three gas ports 35-37 areprovided to regulate the flow of gas into the operating system 100.Nozzle assembly 30 and adjustment knob 20 are in operationalcommunication. Toggling the adjustment knob 20 rotates the nozzleassemble 30 into one of four positions. One position 25 provides thestandard flow of gas, for use when the weapon is being utilized in itsfactory configuration with no accessories. Another position 26 reducesthe flow of gas for use of a silencer with the host firearm, well knownin the prior art. Still another position 28 is provided which introducesmore gas than is needed under normal circumstances, such as when thefirearm is utilizing under powered ammunition or the weapon is fowledwith un-burnt powder and debris. Finally, a position 27 which blocks theflow of gas from the porthole 44 in the gas piston block 10 fromentering the nozzle assembly's 30 internal nozzle 38 and preventing theoperating system of the firearm from cycling the weapon. The adjustmentknob 20 is rotated by the user to select the desired flow of gas. Spring22 and ball detent 23 prevent unintentional movement of the adjustmentknob 20 by interfacing with the notches 25-28 located on the face of theadjustment knob 20.

When a firearm is discharged expanding gases travel down the barrel 101and a small amount of this excess gas is vented through a gas portlocated at the top of the barrel 101. This gas travels through theporthole 44 located in the gas piston housing 10. If the adjustment knob20 and thereby the nozzle assembly 30 are rotated in such a manner as toallow the flow of gas into the operating system 100, one of three gasports 35-37 will be in direct communication with the porthole 44 locatedin the gas piston housing 10. Depending on the use of the firearm theuser will utilize the adjustment knob 20 to select the appropriate gassetting. Gas will enter the nozzle assembly 30 through one of the threegas ports 35-37 located near the proximal end of the nozzle assembly 30,travel thru the internal nozzle 38 and exit the nozzle 30 therebyentering the indirect gas operating system 100 of the host firearm.

When the weapon is dirty, or under-powered ammunition is being utilized,the adjustment knob 20 and thereby the nozzle assembly 30 are rotated sothat gas port three 35 is in communication with the porthole 44 locatedin the gas block 10. When a silencer is being utilized, therebyincreasing the flow of gas into the operating system 100, gas port one36, which is smaller in diameter, should be chosen. This prevents thegas operating system 100 from becoming over-gassed and causingextraction problems, or increased wear of the operating systems 100components. Under normal firing conditions, gas port two 37 is chosenwhich provides the necessary flow of gas into the operating system 100for the firearm to operate under normal firing conditions.

In sum, an adjustable gas block is provided for an autoloading firearmwhich utilizes and indirect gas operating system. Four pre-set positionsare afforded the user of this device. Gas settings which are optimizedfor suppressor use, hard environments, dirty weapons or when firingunder ideal circumstances are provided for. A position which preventsthe flow of gas into the operating system is provided for. This systemdoes not vent excess gas from the gas block into the atmosphere aroundit. Instead excess gas is trapped within the barrel and vented from themuzzle where a flash hider or silencer might allow the gasses to expandand cool.

Another embodiment of the adjustable gas block could eliminate theincreased gas flow setting or the setting which blocks of the flow ofgas.

Still another embodiment of the adjustable gas block could be adapted towork with a direct gas impingement system such as found on M16 stylerifles. The nozzle assembled could be modified to receive the gas tubefound on such system and thereby regulate the flow of gas from thebarrel into the operating system.

While the above drawings and description contain much specificity, theseshould not be construed as limitations on the scope of the invention,but rather as an exemplification of one preferred embodiment thereof.

Accordingly, the scope of the invention should be determined not by theembodiments illustrated, but by the appended claims and their legalequivalents.

1. A firearm utilizing an adjustable gas block comprising: a receiver; abarrel connected to the receiver; a gas operating system; a pistonhaving a front end, back end, and internal void with means tocommunicate with the barrel and gas operating system through a pluralityof ports which are spaced about the back end; a gas block housing havinga receiving channel with a portion of the barrel contained therein, acylindrical bore which runs parallel to the axis of the barrel locatedabove the receiving channel with a port in communication with thebarrel, the cylindrical bore contains the back end of the pistontherein; a rotatable knob is utilized which both receives and rotatesthe piston within the cylindrical bore, said knob has a means to retainand rotate the piston within the cylindrical bore.
 2. A firearmutilizing an adjustable gas block in claim 1 wherein said piston has twoports located about the back end of the piston.
 3. A firearm utilizingan adjustable gas block in claim 1 wherein said piston has three portslocated about the back end of the piston.
 4. A firearm utilizing anadjustable gas block in claim 1 wherein the rotatable knob provides fourpositions of adjustment and is removable retrained by a spring loadeddetent.
 5. A firearm utilizing an adjustable gas block in claim 3wherein at least one of said ports is oversized in proportion to whatwould be a standard size for the barrel being used with the operatingsystem.
 6. In an indirect gas operated firearm having a receiver, astock connected to an end of the receiver, a barrel connected to a frontof the receiver, a handguard connected to the barrel and a gas operatingsystem, wherein the improvement comprises: a gas block with means tosecure about the barrel, the gas block housing has a barrel receivingchannel with a portion of the barrel therein, the housing also has apiston receiving channel with a portion of the piston contained therein;and said piston receiving channel has a void which houses an adjustmentknob, the adjustment knobs is indexable into four positions; and apiston is in operational communication with the barrel and the operatingsystem, the piston communicates with the barrel by a series of portslocated about its periphery, by rotating the adjustment knob the port ofappropriate size is selected and put into communication with theindirect gas operating system and barrel, one port provides a standardflow of gas, one port provides a reduced flow of gas, one port providesa higher than standard flow of gas; a fourth position of adjustment isprovided by the adjustment knob where no port is present on the pistonthereby preventing the communication of the barrel with the indirect gasoperating system.
 7. In an indirect gas operated firearm having areceiver, a stock connected to an end of the receiver, a barrelconnected to a front of the receiver, a hand guard connected to thebarrel and a gas operating system as in claim 6, wherein the gas blockhas a porthole communicating with the piston receiving channel, saidporthole being located so that the piston is connected to the barrel. 8.In an indirect gas operated firearm having a receiver, a stock connectedto an end of the receiver, a barrel connected to a front of thereceiver, a hand guard connected to the barrel and a gas operatingsystem as in claim 7, wherein a means is provided to align the gas blockwith the porthole of the barrel.